Latest ArticlesThe specific crystalline form of a compound remarkably affects its physicochemical properties. Therefore, a detailed analysis of the structural features and intermolecular interactions of a multi-component crystal is feasible to understand the relationships among the structure, physicochemical properties and the formation mechanism. In the present study, three novel cocrystal salt solvates of rhein and berberine were reported for the first time. Various solid characterizations and theoretical computations based on density functional theory (DFT) were carried out to demonstrate the intermolecular interactions. The theoretical computation shows that the strongest interaction existed between berberine cation and rhein anion, and the electrostatic interaction play a dominant role. However, no salt bond was observed between them. Further intrinsic dissolution rate analysis in water shows that the monohydrate exhibits 17 times enhancement in comparison with rhein. The rhein and berberine combined in ionic state in cocrystal salt is the main reason for the solubility improvement. This paper suggests that the interactions between the different components can be visualized and qualitatively and quantitatively analyzed by theoretical computation, which is helpful to understand the relationship between stereochemical structure and physicochemical properties of multi-component complex.
Semiconductor electrocatalysis with weak conductivity can accumulate extremely high carriers at semiconductor-electrolyte interface by self-gating effect, which strongly promotes electrocatalytic efficiency. The correlation between semiconductor carrier mobility and electrocatalysis performance is still unclear. Herein atomic-thin transition metal dichalcogenides based composites have been developed for hydrogen evolution reaction (HER) performed with on-chip microdevices. Electrical and electrochemical measurement of individual flack verified the key role of high carrier mobility for enhanced HER activity. Carrier mobility regulation further demonstrated its high dependence with HER performance under self-gating. Our study provides new insight into the carrier mobility of the semiconductor in the electrocatalysis, paving the way for designing high-performance semiconductor catalysts.
Simultaneous and quantitative detection of multiple exosomal microRNAs (miRNAs) was successfully performed by a surface-enhanced Raman scattering (SERS) assay consisting of Raman probes and capture probes. In this design, the asymmetric core-shell structured Au@Au@Ag nanoparticles were first synthesized by layer-by-layer self-assembly method and modified with different Raman molecules and recognition sequences (polyA-DNA) to prepare the surface-enhanced Raman probes. Then, the streptavidin-modified magnetic beads were used to immobilize the biotinylated DNA capture sequences (biotin-DNA) to obtain capture probes. In the presence of target exosomal miRNAs, the Raman probes and capture probes could bind to the target exosomal miRNAs in the partial hybridization manner. Thus, the developed SERS sensor could indicate the target miRNAs levels in the buffer solution. Using breast cancer-related miRNAs as model targets, the limits of detection of this sensor were determined to be 1.076 fmol/L for synthetic miR-21, 0.068 fmol/L for synthetic miR-126, and 4.57 fmol/L for synthetic miR-1246, respectively. Such SERS sensors were further employed to detect the miR-21 in 20% human serum and the extraction solution of exosomes, respectively. Therefore, simultaneous and multiplex detection of cancer-related exosomal miRNAs by this assay could provide new opportunities for further biomedical applications.
Tailor-made advanced electrocatalysts with high active and stable for hydrogen evolution reaction (HER) play a key role in the development of hydrogen economy. Herein, a N, P-co-doped molybdenum carbide confined in porous carbon matrix (N, P-Mo2C/NPC) with a hierarchical structure is prepared by a resources recovery process. The N, P-Mo2C/NPC compound exhibits outstanding HER activity with a low overpotential of 84 mV to achieve 10 mA/cm2, and excellent stability in alkaline media. The electrochemical measurements confirm that the enhanced HER activity of N, P-Mo2C/NPC is ascribe to the synergy of N, P-codoped and porous carbon matrix. Density functional theory calculations further reveal that the electron density of active sites on Mo2C can be regulated by the N/P doping, leading to optimal H adsorption strength. In this work, the proof-of-concept resource utilization, a microorganism derived molybdenum carbide electrocatalyst for HER is fabricated, which may inaugurate a new way for designing electrocatalysts by the utilization of solid waste.
Conformational regulation among two or more distant sites is not only one of the main pathways to accomplish multiple tasks in complex biological systems but also represents a powerful strategy to obtain stimuli-responsive supramolecular nanoconstructs with tailored physicochemical performance. We herein report the fabrication of a photochromic supramolecular assembly, which can be synergistically activated by the conformational regulation with bis(4, 8-disulfonato-1, 5-naphtho)-32-crown-8 and then reversibly switched by the through-space communication between restricted stilbazolium salt and photochromic dithienylethene. This work demonstrates that the synergistic conformational modulation via intra- and intermolecular interactions can be developed as a generalizable approach to construct more advanced biomimetic nanomaterials.
Detection of nucleoside derivatives has paramount importance because they are the essential biomolecular units for all life. Herein, we report a host-guest approach by using a fluorescent tetraphenylethene-based octacationic cage as host and 8-hydroxypyrene-1, 3, 6-trisulfonic acid trisodium salt (HPTS) as guest and fluorescent indicator to form non-fluorescent 1:1:1 host-(endo-exo)guest complex in water. This new host-(endo-exo)guest complex can be successfully used for detecting nucleosides (e.g., ATP and GTP), DNA (e.g., sm-DNA), and antibiotics (e.g., Penicillin G) with off-on fluorescence response via a competitive host-guest exchange with HPTS as exo-guest in water. Furthermore, this on-off-on fluorescent host-guest complex is also used for cell imaging based on ATP concentration in HeLa cells. Therefore, this study not only provides insight into the construction of a supramolecular probe with on-off-on fluorescence via host-guest complexation and exchange in solution, but also realizes a universal method for detecting and monitoring biomolecules.
The high effective nano-hybrid pour point depressant (PPD) has attracted extensive attention for its potential application in improving the cold flow properties of diesel fuel. In this paper, the nano-hybrid PPD was prepared by melt-blending method using three different alkyl chain lengths (i.e., tetradecyl, hexadecyl, and octodecyl) of n-alkyl methacrylate-maleic anhydride copolymers (R1MC-MA, R1 = C14, C16, C18) and SiO2 nanoparticles. The effect of those nano-hybrid PPDs on the cold filter plugging point (CFPP) and solidifying point (SP) depressing of diesel fuel were studied. Results indicated that nano-hybrid PPD showed much better performance on diesel fuel. The diesel fuel treated with 0.2 wt% C14MC-MA/SiO2 nano-hybrid PPD exhibited the best depression in CFPP and SP by 6 ℃ and 18 ℃, respectively, which higher than that of single C14MC-MA. Viscosity-temperature curves and polarized optical microscopy were conducted to explore the performance mechanism; and results presented that nano-hybrid PPD of C14MC-MA/SiO2 could effectively lower the low-temperature viscosity, and modify the crystallization behavior and crystal morphology of diesel. Therefore, the cold flow properties of diesel were significantly improved.
Donor-acceptor (D-A) conjugated polymers are widely used in photovoltaic applications and heterogeneous catalysis due to their tunable building block and pre-designable structures. Here, a series of adjustable Donor-acceptor (D-A) benzothiodiazole-based conjugated polymers were designed and synthesized. The photocatalytic performance could be improved by fine-tuning the chemical structure by halogen substitution (F or Cl). The polymers exhibited excellent optoelectronic properties and were effective photocatalysts for the degradation of RhB and MO dyes, as well as promoting the oxidative coupling of benzylamines. Complete degradation of RhB and MO occurred in 30 min under visible light radiation, while the yield of benzylamine coupling mediated by superoxide anion was as high as 82%. Systematic characterization methods were used to gain insights on the unique photocatalytic performance of the polymers. Our findings provide further insights into the design and synthesis of benzothiadiazole-based conjugated polymers as promising organic photocatalysts for solar energy conversion.
Supraparticles (SPs), such as assembly of inorganic components with organic, have made tremendous attention in biochemical analysis, which represents a novel but challenging research orientation. Herein, a single-SPs multifunctional fluorescent sensor array has been developed for high-throughput detection of heavy metal ions in biofluids, which is based on an inorganic/organic hybrid SPs consisting of carbon dots (CDs) and an easily available porphyrin [5, 10, 15, 20-tetra(4-carboxyphenyl)porphyrin (TCPP)]. TCPP can aggregate with the CDs to form the assembly (CDs/TCPP SPs) through the electrostatic and π-π stacking interaction. There are two independent and clearly separated fluorescence emission peaks at 470 and 668 nm in the resultant CDs/TCPP SPs under 380 nm excitation. As a proof-of concept design, F470, F668, F668/F470 of SPs are chosen as three sensor components to constitute our sensor array. With the addition of metal ions, three sensor components can generate different fluorescence response patterns for discriminating 11 heavy metal ions via principal component analysis (PCA). Additionally, thiols can readily capture Cu2+ to switch the fluorescence of CDs/TCPP initially altered by Cu2+. Hence, CDs/TCPP-Cu2+ ensemble is further demonstrated to be a powerful sensor array for pattern recognition of 7 thiols and even chiral recognition of cysteine enantiomers. This novel strategy avoids the tanglesome synthesis of multiple sensing probes and dedicates an innovative method for the facile establishment of tongue-mimic sensors, which would prospectively sprout more homologous assumptions to broaden its application toward more biosensing fields.
Self-assembly is a powerful approach in molecular engineering for biomedical applications, in particular for creating self-assembling prodrugs. Here, we report a self-assembling prodrug of the anticancer drug gemcitabine (Gem) based on amphiphilic dendrimer approach. The prodrug reported in this study demonstrates high drug loading (40%) and robust ability to self-assemble into small nanomicelles, which increase the metabolic stability of Gem and enable entry into cells via endocytosis, hence bypassing transport-mediated uptake. In addition, this prodrug nanosystem exhibited an effective pH- and enzyme-responsive release of Gem, resulting in enhanced anticancer activity and reduced toxicity. Harboring advantageous features of both prodrug- and nanotechnology-based drug delivery, this self-assembling Gem prodrug nanosystem constitutes a promising anticancer candidate. This study also offers new perspectives of the amphiphilic dendrimer nanoplatforms for the development of self-assembling prodrugs.
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